Imagine a cowboy, seated on his horse at the end of a long day. Together, they stand on a ridge, overlooking the valley below. The sun setting beyond the mountains silhouettes them. Near the pair, also in silhouette, is a tall cactus with a couple of arms raised to the sky. The cactus is a saguaro (pronounced, “Sah-wah’-ro,) and, along with the cowboy, has become the symbol of the southwest.

Habitat and Life Cycle

[ad#Google Adsense]The saguaro grows only in the Sonoran Desert of extreme southeastern California, southern Arizona and adjoining northwestern Mexico, usually below elevations of 3,500 feet. It prefers desert slopes and flat areas. The Saguaro grows very slowly — perhaps an inch a year and often starts life in the shelter of a “nurse tree” — a palo verde, ironwood or mesquite tree. These baby cactus are often very difficult to locate since the nurse tree’s limb effectively cover it.

As the saguaro continues to grow, its much older nurse tree may die, possibly due to competition from the saguaro for water and nutrients in the immediate area. It can eventually grow to great height, 15 to 50 feet. The largest cactus are estimated to be 200 years old, have five or more arms, and weigh as much as six tons. The plant doesn’t reach maturity until it has grown its first arm somewhere around 50 to 70 years, although it does begin to produce flowers at around age 35.

The saguaro flowers in late April and early May. It may bloom for up to a month, producing one or two flowers each night. The night-blooming flowers, about 3 inches wide, have many creamy-white petals around a tube about 4 inches long — a tube which collect sweet, sweet nectar. These waxy white flowers attract many species of birds, bats and insect who dine on the sweet nectar and pollinate the flowers. In the morning sun, the flowers close and begin producing fruit assuming they were successfully pollinated. The cycle is repeated the following night with a few more flowers — up to 200 flowers can be produced by a single saguaro during the season.

The 3-inch, oval, green fruit ripens just before the fall rainy season, splitting open to reveal the bright-red, pulpy flesh and as many as 4,000 seeds to a single fruit. All desert creatures seem to relish the ripening fruit, which provides moisture and energy-rich food during the very dry and hot season that precedes the Monsoon rains.

When the fruit and seeds are eaten by certain animals, like coyote or cactus wrens, the seeds pass through their digestive system completely unharmed and are distributed throughout the desert. Oddly enough, other creatures are able to completely consume the seeds, like doves and quail. If the seed is deposited on fertile ground with a nurse tree close by, a new baby saguaro is born.

Crested Saguaro

About 1 in 250,000 saguaro produces a fanlike form which is referred to as crested or cristate. Some scientists speculate that the crest is caused by a genetic mutation, while others say it is the result of a lightning strike or freeze damage. Whatever the cause, crested saguaro are a protected species and, in the state of Arizona, it is illegal to move them.

Water Storage

The saguaro has a very shallow root system for its height and weight. The tap root only goes down about three feet and is actually a tangled pad of roots with numerous stout roots no deeper than a foot radiating out from the base. Smaller roots run out across the desert floor to a distance equal to the height of the cactus and wrap about rocks to provide anchorage from the wind. During a rain storm, the cactus absorbs as much water as possible (hence the weight of up to 6 tons). To accommodate the influx of water, the pleats of the saguaro expand like an accordion, allowing the “barrel” and arms of the cactus to store water for years. However, it is not unusual for a heavy Monsoon rain to turn the ground into a semi-liquid mess, and that, coupled with strong winds, can topple these mighty giants.

The plant can lose up to 82 percent of its moisture before it dies of dehydration. In times of little rain, shallow roots near the soil’s surface can capture the moisture of even the lightest rainfall.

Because a saguaro can store so much water, it can be subject to damage by freezing temperatures. Yes, the nighttime temperature in the Sonoran Desert can drop into the 20s at night. The water inside the stored ribs, especially in the arms, can freeze and expand, weakening the arm. The weakened arm is often pulled toward the ground and warped. Instead of pointing at the sky, the arms are twisted into grotesque shapes and can create rather eerie shapes, especially at dusk.

Symbiotic Relationships

Many animals call the saguaro cactus home. The Gila woodpecker and the gilded flicker chisel nests in the pulpy flesh. When the flickers and woodpeckers leave, the abandoned nests are taken over by elf owls, screech owls, purple martins, finches and sparrows. The Harris Hawk and Redtailed Hawk often use the saguaro for nesting and hunting platforms. Nests are constructed among the arms of the larger saguaro.

Native American Staple

This saguaro was an especially important food and resource to Native Americans of the region who used the flesh, seeds and juice and many other parts of the cactus to survive. The Hohokam used the woody ribs of the saguaro to construct the framework for the walls of their homes. To this day, dozens of Native American tribes collect the sweet fruits and use them to a make ceremonial wine, jelly, and candies. The seeds are used as feed for chickens.

State Flower of Arizona

In 1901 the saguaro’s blossom was adopted as the official territorial flower, and later, in 1931, it was confirmed as the state flower. The Arizona state flower is not only important to the native people and desert wildlife, but is also a great symbol of the southwest. Images and pictures of the southwest often show the stately saguaro at sunrise or sunset, standing tall and proud in silhouette.